Establishment and biological characterization of radioresistant colorectal cancer cell lines

Radiotherapy resistance is a major cause of recurrence and metastasis in colorectal cancer (CRC). We established radiotherapy-resistant cell lines to explore the molecular mechanisms of radiotherapy resistance in CRC. HT29 and HCT116 cells were subjected to repeated irradiation at 2 Gy to establish these lines. CCK-8 assay, colony formation, and xenograft tumor experiments were used to detect the radiosensitivity of the cells. DNA damage repair proteins, GSH content, and intracellular ROS were also assayed in parental and resistant cells. We successfully established HT29R and HCT116R radioresistant cell lines after fractionated irradiation, and the cells showed significant tolerance to further irradiation compared with the parental cells and a stronger capacity for DNA damage repair. Meanwhile, ionizing radiation significantly reduced GSH in HT29 and HCT116 parental cells but had no effect on GSH content in resistant cells. These results demonstrate that radioresistant colorectal cancer cell lines were successfully established by the method of continuous irradiation with 2 Gy. This provides a basis for further exploration of the mechanism of colorectal cancer radiotherapy resistance.